تاثير چينه نگاري مكانيكي بر ميزان كوتاه شدگي ، هندسه و سبك چين خوردگي در پهنه لرستان ، زاگرس چين خورده - رانده

The Effect of Mechanical Stratigraphy on Deformation Style in Lorestan Subzone, Zagros Fold-Thrust Belt

Structural analysis of folds across the western part of the Lorestan zone in Zagros fold-thrust belt showed that geometry of the folds are varies in different structural levels and leads to change in the folds style to depth. Competency contrast of rock units is the main controlling parameter of such a diverʹs behavior. Rock units with lower competency, as detachment surfaces, play a significant role in deformation style and its diversity down to depth. The Pabdeh, Gurpi and Illam Formation which are overlaying on incompetent Garu Formation compose outcrops of the study area. It is interpreted that the Garu and Pabdeh Formations are the major detachment zones control fold style across the study area. Geometric test of the folds constrain the effect of the detachment zones on variation of deformation style between their upper and lower rock units. In such a manner that folds in lower units to these detachments have larger wavelength comparing to ones developed within the overlying units. Similarly, strain partitioning within the whole sequence between competent and incompetent rock units demonstrate that change in geometry and folding styleʹfrom surface to depth, in Lorestan zone, is mainly affected by diversity in mechanical behavior of rock units or in other words the effect of mechanical stratigraphy.